Solar sail launch system and solar sail attitude control system

Abstract

Fuel less ACS for solar sails, using furl- and unfurl able ballast-sail-foil-segments for simultaneously displacement of center of mass and center of solar radiation pressure into opposite directions to each other. Solar-Sail-Launch-System for direct launch of the System-Sail including already docked in daughter units and payload in the sailcraft's central docking station. Unlike todays launch able solar sail designs the System-Sail features ample solar cell arrays and additional SEP-thruster-units for steering and propulsion, while the solar sail rather serves for longtime fuel less attitude controls and station keeping. The SEP-Sailcraft may also serve as a carrier-ship for daughter-units in asteroid exploration missions and is able to deliver prospector landers back to LEO with furled in foils.

1. A solar sail launch system comprising a thruster-powered solar sail mothership spacecraft in combination with a launch vehicle, the solar sail mothership spacecraft comprising:
 a ring structure of connected rings, 
 a plurality of telescoping masts each having a pivotal attachment at a first end to said ring structure and each pivotally supporting at a second end a sail foil roll with sail foil furled onto the roll; 
 the launch vehicle comprising: 
 a payload compartment and a rotatable platform, 
 the payload compartment being defined by a plurality of petal segments corresponding in number to the number of said telescoping masts of the solar sail mothership spacecraft, and so mounted that said petal segments can be pivoted to open the payload compartment; 
 wherein the solar sail mothership spacecraft is contained in a stowed condition within the payload compartment with said ring structure mounted on the rotatable platform and with the telescoping masts in a retracted condition; 
 the solar sail launch system further comprising: 
 a pivoting mechanism for pivoting said petal segments, whereby each petal segment is configured to pull a corresponding one of said telescoping masts from a stowed position to a deployed position by pivoting the telescoping mast about said pivotal attachment to said ring structure, said telescoping masts all lying substantially in a common plane in their deployed positions; 
 means for telescoping each of said telescoping masts from said retracted condition to an extended condition; 
 means for pivoting each of said sail foil rolls about said second end of the respective telescoping mast to an operational position in which the sail foil is unfurled from said sail foil roll, whereby said sail foil roll extends transversely relative to the respective telescoping mast; 
 means for detaching said solar sail mothership spacecraft from said launch vehicle; and 
 means for selectively unfurling and reefing said sail foils on said sail foil rolls to enable the attitude and thrust vector of the solar sail mothership spacecraft to be controlled by the effects of solar radiation pressure impinging on and deflecting off of the sail foils and the center of mass shift caused by the furling and unfurling of the sail foils. 
 
     
     
       2. The solar sail launch system of  claim 1 , wherein the ring structure comprises a first plurality of connected rings arranged in a spaced-apart orientation and connected by frame elements, said first plurality of connected rings defining a cylindrical volume which encloses a plurality daughter units and a payload, said daughter units and payload being attached to the ring structure by fastening means consisting of docking brackets and winch devices, wherein the cylindrical volume is configured as a docking station,
 the ring structure further comprising a second plurality of connected rings encircling said cylindrical volume such that the second plurality of connected rings is co-axial to the first plurality of connected rings, said second plurality of connected rings lying in a common plane, wherein thruster units and solar cell arrays are attached to said second plurality of connected rings. 
 
     
     
       3. The solar sail launch system of  claim 2 , wherein said docking brackets are configured to allow movement of said daughter units relative to said docking station for attitude control and steering, and wherein said winch devices are configured to move said payload relative to said docking station for attitude control and steering. 
     
     
       4. The solar sail launch system of  claim 2 , wherein the solar sail mothership spacecraft is equipped with a plurality of thruster pairs which are mounted in a shared jet tube to the second plurality of connected rings, whereby each thruster pair comprises thrusters oriented to provide thrust in opposite directions, thereby enabling the solar sail mothership spacecraft to steer, move, and also reverse thrust directions by switching to the opposite thrusting thrusters. 
     
     
       5. The solar sail launch system of  claim 1 , wherein said pivoting mechanism for pivoting said petal segments comprises a plurality of sail foil roll winches, each of which is mounted on a respective one of said petal segments and incorporates a line connected to a respective one of said sail foil rolls, whereby each sail foil roll winch can effect said pivoting of said respective sail foil roll to its operational position, said sail foil rolls each further comprising a snap-in mechanism being provided to lock each said sail foil roll into said operational position. 
     
     
       6. The solar sail launch system of  claim 5 , wherein the lines of said sail foil roll winches comprise predetermined breaking points, whereby said lines can be broken by the forces exerted by the sail foil roll winches once said sail foil rolls have been locked into said operational position. 
     
     
       7. The solar sail launch system of  claim 1 , wherein said ring structure is releaseably secured to said rotatable platform by means of holding damps, and wherein said telescoping masts each comprise nested telescoping sections comprising spring-biased locking pin assemblies, and wherein means for rotating said rotatable platform cause rotation of said platform, whereby centrifugal forces are generated through rotation which pull said telescoping masts into their extended conditions in which each nested mast section can be locked by the action of said spring-biased locking pins. 
     
     
       8. The solar sail launch system of  claim 7 , wherein each spring-biased locking pin assembly comprises a spring located in an open-ended sleeve extending transversely to one section of a telescoping mast, and the spring acts on a respective pair of locking pins, each pin extending from a respective end of the sleeve, to an adjacent section of the telescoping mast within which said nested section slides, the outer mast segment being provided with holes in which the pins pressing outwards from the nested section can engage when said nested mast section is stopped in said extended condition at a pullout lock which is attached to the end of each outer segment. 
     
     
       9. The solar sail launch system of  claim 1 , wherein each sail foil roll is provided with motors for rotating the roll about its own axis. 
     
     
       10. The solar sail launch system of  claim 1 , wherein each sail foil roll is provided with a motor for rotating said roll of sail foil about the axis of the telescoping mast upon which it is supported. 
     
     
       11. The solar sail launch system of  claim 1 , wherein of said sail foils two different sail foil types exist, the regular sail foils, which are consisting of a foil segment only and the steering sail foils, said steering sail foils each comprise a foil segment at a proximal end and a ballast segment at a distal end with respect to said plurality of connected rings, wherein said ballast segments are made of a material that is heavier and thicker than the foil segments, wherein said steering sail foils are arranged in steering pairs such that the two steering sail foils of a steering pair are located at opposite sides with respect to the second plurality of connected rings, said means for selectively unfurling and reefing said sail foils of the solar sail mothership spacecraft being capable of moving the center of mass of the solar sail mothership spacecraft by selectively unfurling and reefing the sail foils of said steering pairs. 
     
     
       12. The solar sail launch system of  claim 11 , wherein the selective unfurling and reefing of the solar sails changes the center of solar radiation pressure of the solar sail mothership spacecraft, and wherein the solar sail mothership spacecraft is steered by changing the center of mass relative to the center of solar radiation pressure, the center of mass being changed by selectively unfurling and reefing said sail foils comprising said ballast segments and by moving said daughter units and payload relative to the ring structure.